Communication apparatus managing other node and communication apparatus managed by other node

ABSTRACT

A communication apparatus as a node of a communication network comprises a reading device that reads management information representing management status of a dominated node stored in the dominated node connected via the communication network, a writing device that writes identification information for managing the dominated node into the dominated node when the management information does not include identification information of other dominating node, and a management device that manages the dominated node. The communication apparatus is complied with the IEEE1394 Standard and capable of managing the other nodes on the communication network.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.10/370,167 filed Feb. 18, 2003, which in turn is based on JapanesePatent Applications 2002-043588, filed on Feb. 20, 2002, the entirecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

A) Field of the Invention

This invention relates to a communication apparatus that has a dominatednode and a dominating node, and more specifically, a dominating nodethat can manage other node and a dominated node that is managed by thedominating node.

B) Description of the Related Art

IEEE 1394 Standard published by the Institute of Electrical andElectronics Engineers is known as a serial bus interface standard whichcan execute a voluminous and rapid digital data transmission. Aninterface based on the IEEE1394 Standard or a device equipped with theinterface (hereinafter both are called the IEEE1394 device) is equippedwith an IEEE1394 bus protocol formed of hardware (a lower layer) thatforms one node and protocols (an upper layer) such as a device control,an isochronous transmission control, etc. by means of software placedover the lower layer.

FIG. 12 is a schematic block diagram showing an example of protocolstack of a general audio visual (AV) device equipped with the mLAN®upper layer. The mLAN standard is connection management technologyrelating to a music data digital network for music performance data andaudio data, the technology using the IEEE 1394 Standard and is anapplication located in the upper application.

The lower layer is, for example, constituted of each layer of a physicallayer, a link layer, a transaction layer and a serial bus management.

The physical layer regulates the physical interface and the electricinterface and is generally made of hardware. In the link layer, aone-way transmission service called sub-action and a packet handler thatis a packet transmission/reception service are provided. The link layeris also generally made of hardware as same as the physical layer. In thelink layer, for example, services concerning to the asynchronoustransmission and the isochronous transmission are provided.

Also, especially in the isochronous transmission, since a signal thatneeds a rapid process such as an audio signal, a video signal and thelike is managed, all the services are provided in the link layer that ishardware.

The transaction layer executes a process concerning to the asynchronoustransmission. The transaction is a data transmission of arequest-response type. There are three transaction types, namely, a readtransaction, a write transaction and a lock transaction.

The read transaction is a transaction used for reading data from aspecific target address space. The write transaction is a transactionused for writing data in a specific target address space. The locktransaction is a transaction used for renewing data in a specific targetaddress space in accordance with reference data.

The bus management is a module for intensively managing resources on theserial bus. The bus management includes management of power supplies,management of a topology map and a speed map, management of isochronousresources, and the like.

The upper layer is software for managing the lower layer and the wholenode, and is constituted of, for example, the 1394AV protocols(IEC-61883) and mLAN upper layer.

The AV protocols define a common isochronous packet (CIP) format forexpressing the data contents of an isochronous packet, a connectionmanagement protocol (CMP) for managing connections by defining a virtual“plug”, a function control protocol (FCP) for managing other devicesconnected to the IEEE1394 bus, and the like.

The mLAN upper layer is a protocol layer for transmission of audio/musicinformation in accordance with the IEEE1394 standard. The mLAN upperlayer is constituted of an audio/music information transmission protocoland a connection management protocol both complied with the 1394AVprotocols.

The audio/music information transmission protocol is used for adding theformat for transmitting audio/music information to the definition ofCIP. The connection management protocol is used for performingautonomous connection management of each node by using an intelligentCMP.

All IEEE1394 devices connected to an IEEE1394 bus have the upper andlower layers although the functions thereof are different more or less.

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@ The upper layer is more complicated than the lower layer. Therefore,hardware resources necessary for the upper layer increase more than thelower layer. The manufacture cost rises if the upper layer is used forall IEEE1394 devices.

The upper layer is more relevant to a user interface than the lowerlayer. Therefore there are many chances of feeding back revisionrequests from users. Although it is desired that the upper layer has thestructure easy to match a new specification, the manufacture cost risesif the structure of the upper layer of each of all IEEE1394 devices ismade easy to upgrade.

In a section of a preferred embodiment in Japanese Patent Application2001-220895, the application being filed by the same applicant of thepresent application, it is suggested that other dominating node executesby proxy a function of the dominated node that does not have the upperlayer. In the invention of Japanese Patent Application 2001-220895, aGUID of the dominating node to execute a function by proxy of the upperlayer is written in a storage area of the dominated node. Therefore, afunction of the dominated node can be used from other general node viathe dominating node.

However, according to the above-described invention, when the dominatingnode that has the GUID written in the storage area does not response forsome reason, other general node cannot use the dominated node.

Also, when the dominating node of a newer version participates in thenetwork, and in the case that it is more effective for using thefunction of the dominated node when other dominating node executes it byproxy, other dominating node could not use the dominated node that ismanaged by other dominating node.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an apparatuscomplied with the IEEE1394 Standard and capable of being manufactured ata low cost.

It is another object of the present invention to provide an apparatuscomplied with the IEEE1394 Standard and capable of managing other nodes.

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Further, it is another object of the present invention to provide anapparatus complied with the IEEE1394 Standard and capable of managingthe node that is managed by other node temporarily.

According to one aspect of the present invention, there is provided acommunication apparatus as a node of a communication network,comprising: a reading device that reads management informationrepresenting management status of a dominated node stored in thedominated node connected via the communication network; a writing devicethat writes identification information for managing the dominated nodeinto the dominated node when the management information does not includeidentification information of other dominating node; and a managementdevice that manages the dominated node.

According to another aspect of the present invention, there is provideda communication apparatus as a node of a communication network,comprising: a reading device that reads management informationrepresenting management status of a dominated node stored in thedominated node connected via the communication network; a requestingdevice that requests permission to manage the dominated node to otherdominating node when the management information includes identificationinformation of the other dominating node; and a management device thatmanages the dominated node in accordance with the permission of theother dominating node.

According to further aspect of the present invention, there is provideda communication apparatus as a node of a communication network,comprising: a reading device that reads management informationrepresenting management status of a dominated node stored in thedominated node connected via the communication network; a confirmingdevice that confirms whether other dominating node is managing thedominated node or not when the management information includesidentification information of the other dominating node; and amanagement device that manages the dominated node when the otherdominating node is not managing the dominated node.

According to yet further aspect of the present invention, there isprovided a communication apparatus forming one dominated node of acommunication network, comprising: a lower layer that is managed byother node of the communication network and has a communication devicethat transmits/receives a signal to/from other node connected to thecommunication network; and a storage device that stores managementinformation representing a management status of the lower layer.

According to still further aspect of the present invention, there isprovided a communication system, comprising: a dominated node comprising

a lower layer that is managed by other node of the communication networkand has a communication device that transmits/receives a signal to/fromother node connected to the communication network, and a storage devicethat stores management information representing a management status ofthe lower layer; a first dominating node comprising a reading devicethat reads the management information stored in the dominated nodeconnected via the communication network, a writing device that writesidentification information for managing the dominated node into thedominated node when the management information does not includeidentification information of other dominating node, a management devicethat manages the dominated node, a request receiving device thatreceives a management request for managing the dominated node from otherdominating node, and a responding device that responds to the otherdominating node with permission to manage or rejection of the request inaccordance with the received request; and a second dominating nodecomprising a reading device that reads the management information storedin the dominated node connected via the communication network, arequesting device that requests permission to manage the dominated nodeto the first dominating node when the management information includesidentification information of the first dominating node, and amanagement device that manages the dominated node in accordance with thepermission of the first dominating node.

According to the present invention, it is possible to provide anapparatus complied with the IEEE1394 Standard and capable of beingmanufactured at a low cost.

According to the present invention, it is also possible to provide anapparatus complied with the IEEE1394 Standard and capable of managingother nodes.

According to the present invention, it is also possible to provide anapparatus complied with the IEEE1394 Standard and capable of managingthe nodes that are managed by other nodes temporarily.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an example of an IEEE1394 bus 1according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing an example of a CSR memory of adominated node 3 a or 3 b according to the embodiment of the presentinvention.

FIG. 3 is a schematic diagram showing an example of a CSR memory of adominating node 4 according to the embodiment of the present invention.

FIG. 4 is a block diagram showing communications between general nodes 2a and 2 b.

FIG. 5 is a block diagram showing communications between the generalnode 2 a and dominated node 3 a according to the embodiment of thepresent invention.

FIG. 6 is a block diagram showing communications between the generalnode 2 a and dominated node 3 a via the dominating node 4 according tothe embodiment of the present invention.

FIG. 7 is a flow chart showing a management setting process fordominated nodes to be executed by the dominating node 4 according to theembodiment of the present invention.

FIG. 8 is a flow chart showing a process of performing communicationsillustrated in FIG. 6 to be executed by each node.

FIG. 9 is a flow chart showing a confliction adjustment processaccording to the embodiment of the present invention.

FIG. 10 is a flow chart showing a management right claiming processaccording to the embodiment of the present invention.

FIG. 11 is a flow chart showing a confirming process to other dominatingnode in the dominating node 4 according to the embodiment of the presentinvention.

FIG. 12 is a schematic diagram showing an example of a protocol stack ofa general audio/visual (AV) apparatus having an mLAN upper layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a block diagram showing an example of an IEEE1394 bus 1according to an embodiment of the present invention.

The IEEE1394 bus 1 of the embodiment is structured by connecting, withIEEE1394 cables, general nodes 2 a and 2 b with their upper and lowerlayers, a dominated node 3 a without an upper layer, and a dominatingnode 4 (4 a and 4 b) with its upper and lower layers and upper layers ofother nodes (e.g., upper layers of the dominated nodes 3 a and 3 b).

Each of the general nodes 2 a and 2 b may be one of an electronicmusical instrument, an acoustic machine, an AV apparatus, a personalcomputer, an external storage device of various types and the like eachhaving an IEEE1394 interface. The general node 2 a has the upper layer Aand lower layer A, and the general node 2 b has the upper layer E andlower layer E.

The dominated node 3 a may be one of an electronic musical instrument,an acoustic machine, an AV apparatus, a personal computer, an externalstorage device of various types and the like each having an IEEE1394interface. For example, the dominated node 3 a may be a powered speakeror the like. The dominated node 3 a has no upper layer, but it isprovided with only the lower layer B. Since the dominated node 3 a doesnot have an upper layer, the dominated node 3 a itself cannot normallycommunicate with the general node 2 a or 2 b by using a protocol definedby the upper layer.

Since the dominated node 3 a is not provided with the upper layer, itcannot process by itself a command based upon the 1394AV protocol and acommand based upon the mLAN standards which commands are generallyprocessed by the upper layer. Since various transactions, isochronoustransmission and the like are processed by the lower layer, thedominated node 3 a itself can process them.

For example, if the dominated node 3 a is a powered speaker, voicesignals and the like to be reproduced are generally transmitted throughisochronous transmission so that they can be processed only by the lowerlayer. However, connection setting of a reception channel, volumecontrol and the like cannot be processed by the dominated node 3 aitself with only the lower layer, because a command is received by theupper layer and the upper layer writes data in a function register (ahardware register in the lower layer) corresponding to the command byanalyzing the command.

The dominated node 3 a is a dominated node and stores an ID foridentifying the type of an upper layer necessary for the dominating nodethat manages the dominated node into a Control and Status Registers(CSR) memory to be described later. The dominated node 3 a also stores aGlobal Unique Identifier (GUID) of the dominating node currentlymanaging the dominated node in the CSR memory.

The structure of the dominated node 3 b is approximately the same asthat of the dominated node 3 a, excepting that the dominated node 3 bhas an upper layer D′ and the lower layer D. The dominated node 3 b maysuspend the function of its upper layer D′ to be managed by the upperlayer D of the dominating node 4. The upper layer D′ of the dominatednode 3 b may manage only some functions and missing functions may bemanaged by the upper layer D of the dominating node 4. Functions of theupper layer D′ of the dominated node 3 b can be executed or suspended inresponse to an external command.

Similar to the dominated node 3 a, the dominated node 3 b is a dominatednode and stores an ID for identifying the type of an upper layer in theCSR memory, ID being necessary for the dominating node that manages thedominated node. If functions of the upper layer D′ of the dominated node3 b are to be suspended, the dominated node 3 b stores a GUID of thedominating node currently managing the dominated node in the CSR memory.

The dominating nodes 4 a and 4 b (hereinafter both or either one of thedominating nodes 4 a and 4 b are called the dominating node 4) may beone of an electronic musical instrument, an acoustic machine, an AVapparatus, a personal computer, an external storage device of varioustypes and the like each having an IEEE1394 interface. For example, thedominating node 4 is a personal computer having an external storagedevice. The dominating node 4 has the lower layer C (the lower layer Fin the case of the dominating node 4 b) and its upper layer C (the upperlayer F in the case of the dominating node 4 b) and in addition to theupper layers B and D for managing the lower layers of the dominatednodes 3 a and 3 b. These upper layers B and D are used as the proxies ofthe upper layers of the dominated nodes 3 a and 3 b so that thedominated node 3 a or 3 b can communicate with the general node 2 a or 2b by using the protocol defined by the upper layer.

The dominating node 4 stores a GUID of a dominated node that thedominating node can dominate, in correspondence with software (upperlayer) for managing the dominated node. FIG. 2 is a schematic diagramshowing an example of a CSR memory of a dominated node 3 a or 3 baccording to the embodiment of the present invention.

The CSR memory of the dominated node 3 a or 3 b is constituted of, forexample, a CSR core register, a serial bus register, a configuration-ROMhaving Y address information, and node-specific registers having an AV/Carea and a Y area.

The CSR core register and serial bus register have the structure similarto that of a known IEEE1394 device. The Y address information is madepublic to other nodes (particularly the dominating node). The Y addressinformation includes the addresses of a read-only area and a read/writearea respectively in the Y area, and the addresses of a dominating nodeID storage area, a lower layer function register area and other areasrespectively in the read/write area.

The dominating node ID storage area is divided into storage areas M1 toM4.

In the storage area M1, a GUID of a dominating node that manages its owndevice (a dominated node) is stored. When there is no dominating nodethat manages its own device (the dominated node), a value “0” is stored.An initial value is “0”. Also, contents in the storage area M1 maypreferably be reserved at the time of power off.

The storage area M2 is a flag showing whether temporary management by adominating node other than the dominating node stored GUID in thestorage area M1 is possible or not. When the temporary management ispossible, a value “1” is stored. When it is not possible, a value “0” isstored. The temporary management by a dominating node other than thedominating node stored GUID in the storage area M1 is possible forexample, when the dominating node that the GUID is stored in the storagearea M1 is in a state of power off or inactive, and when there is nodominating node on the same bus.

The storage area M3 is a flag showing whether its own device (thedominated node) is temporarily managed by the dominating node other thanthe dominating node stored GUID in the storage area M1 or not. When itis managed temporarily, a value “1” is stored, and when it is not, avalue “0” is stored.

In the storage area M4, a GUID of a dominating node (hereinafter calleda temporal dominating node) that manages its own device (the dominatednode) temporarily is stored. When there is no temporal dominating node,a value “0” is stored, and an initial value is “0”. Also, it maypreferably be cleared at a time of power off.

The nodes (dominating nodes) stored the GUID in the storage area M1 orM4 read the Y address information, and can detect address of necessaryregister for managing the dominated node.

The GUID of the dominating node that manages its own device is stored inthe storage area M1 or M4 to open to the public. Therefore, thedominating node that manages at the present time can be recognized, anda confliction of the dominating nodes can be prevented.

Also, the state (whether the dominated node is managed or not) of thedominated node at the present time is stored in the storage area M2 orM3 to open to the public. Therefore, the present state can easilyrecognized from other node.

Only a node whose GUID is stored in storage area M1 or M4 may bepermitted to write data in a node-specific register. In this case, evenif dominating nodes whose GUID's are not written in the dominating IDexist on the same bus, confliction between the dominating nodes can beprevented.

Also, the dominating node ID storage area is provided in the Y area, andit may be provided in an area where reading/writing is possible from thedominating node. FIG. 3 is a schematic diagram showing an example of theCSR memory of the dominating node 4 according to the embodiment.

The CSR memory of the dominating node 4 is constituted of, for example,a CSR core register, a serial bus register, a configuration-ROM, andnode-specific registers having an AV/C area.

The CSR core register and serial bus register have the structure similarto that of a known IEEE1394 device. The structure of other parts isgenerally the same as that of the CSR memory of the dominated node 3 aor 3 b shown in FIG. 2.

The CSR memory of the dominating node 4 features in that it storesinformation of the dominating node in the configuration-ROM as well asfunction information of dominated nodes under management of thedominating node. Since the function information of each dominated nodeunder management is stored in the configuration-ROM, the other nodeconnected to the network interprets as if the dominating node featuresthe functions of the dominated node.

FIG. 4 is a block diagram showing communications between the generalnodes 2 a and 2 b. First, the general node 2 b receives from the generalnode 2 a (on the transmission side) a write-command instruction (packet1) relative to an address corresponding to a function of the upper layerE. Next, in accordance with this write instruction, the lower layer E ofthe general node 2 b (on the reception side) executes the write-commandrelative to the address corresponding to the function of the upper layerE.

Thereafter, the upper layer E of the general node 2 b acknowledges thewrite instruction (packet 1) and supplies the lower layer E with thewrite instruction relative to a register (function register)corresponding to the command. Namely, the upper layer E analyzes thereceived command to allow control data corresponding to the contents ofthe command to be written in the register (function register) of thelower layer E corresponding to the function to be managed by thecommand. With the above-described operations, the lower layer E canperform the operation corresponding to the command transmitted from thegeneral node 2 a, in accordance with the control data written in theregister.

After the control data is normally written, the lower layer E of thegeneral node 2 b transmits a packet 2 to the general node 2 a, thepacket 2 indicating that the write instruction was executed normally.

The nodes having the upper layer can manage each other by writing datain the function register via their own upper layers. FIG. 5 is a blockdiagram showing communications between the general node 2 a anddominated node 3 a according to the embodiment. In this example, it isassumed that the dominating node 4 is not connected to the IEEE1394 bus1.

The dominated node 3 a receives, from the general node 2 a (on thetransmission side), a write-command instruction (packet 1) relative tothe address corresponding to a function of the upper layer. Inaccordance with this write instruction, the lower layer B of thedominated node 3 a (on the reception side) tries to execute thewrite-command. However, since the dominated node 3 a is not providedwith the upper layer, the address corresponding to the function of theupper layer does not exist. Therefore, the lower layer B transmits anerror (packet 2) to the general node 2 a. Namely, since the dominatednode 3 a is not provided with the upper layer, the write-commandcorresponding to the received packet 1 fails so that the control of thelower layer B corresponding to the command will not be performed.

Since the dominated node 3 a returns the error relative to the commandcorresponding to the function of the upper layer, it can know that thedominated node 3 a is not provided with the upper layer. In thisembodiment, as shown in FIG. 6, the dominating node 4 is provided withthe upper layer of the dominated node 3 a and communicates with thegeneral node 2 a as a proxy of the dominated node 3 a.

FIG. 6 is a block diagram showing communications between the generalnode 2 a and dominated node 3 a via the dominating node 4 according tothe embodiment. The dominating node 4 can manage the dominated node 3 abecause the dominating node 4 has already been set by a dominated nodemanagement setting process to be later described.

First, the lower layer C of the dominating node 4 receives from thegeneral node 2 a (on the commanding side) a write-command instruction(packet 1) relative to an address corresponding to a function of theupper layer B of the dominated node 3 a.

Next, in accordance with the received write instruction, the lower layerC of the dominating node 4 writes a command relative to the addresscorresponding to the function of the upper layer B. Thereafter, theupper layer B detects the address of a function register of the lowerlayer B of the dominated node 3 a corresponding to the functiondesignated by the command. A write instruction (packet 2) for controldata corresponding to the command relative to the detected address istransmitted to the dominated node 3 a.

Thereafter, the lower layer B of the dominated node 3 a executes thereceived write instruction (packet 2). Namely, the control data iswritten relative to the address corresponding to the function registerof the lower layer B, and the process result (packet 3) is transmittedto the dominating node 4. In accordance with the written control data,the lower layer B executes an operation corresponding to the commandtransmitted from the general node 2 a to the upper layer B of thedominating node 4.

Upon reception of the process result (packet 3) from the dominated node3 a, the dominating node transmits a response (packet 4) to the commandto the general node 2 a that is the commanding side and sent thecommand.

The general node 2 a receives the response (packet 4) from thedominating node 4 and recognizes that the process was performednormally. The dominating node 4 becomes a proxy of the role that theupper layer of a dominated node originally plays. A signal to beprocessed at the upper layer is transmitted to the dominated node byusing the format that the lower layer can process. In this manner, awrite-command or the like relative to the dominated node without theupper layer can be performed.

FIG. 7 is a flow chart showing a dominated node management settingprocess to be executed by the dominating node 4. This dominated nodemanagement setting process is activated each time a normal bus reset isexecuted. The bus reset occurs when the topology changes such as when anew node is connected to the bus and when the connected node isdisconnected from the bus.

At Step SA1, the dominated node management setting process starts andthe flow advances to the next Step SA2.

At Step SA2, the dominated node management setting process isinitialized. Thereafter, the flow advances to the next Step SA3.

At Step SA3, GUID of each dominated node to be managed is read from arewritable memory (e.g., the read/write area in FIG. 2). For theconvenience of following description, it is assumed that the dominatingnode of this embodiment has already memorized one GUID of a dominatednode in the rewritable memory. In a practical case, the dominating nodemay memorize one GUID, a plurality of GUID's or no GUID of the dominatednode(s). GUID of the dominated node to be managed may be input by auser. GUID of the dominated node, which received the write instructionrelative to the address corresponding to the function of the upper layerand returned the error as shown in FIG. 5, may be read from theconfiguration-ROM of the dominated node. After GUID of the dominatednode to be managed is read, the flow advances to the next Step SA4.

At Step SA4, GUID of each node connected to the IEEE1394 bus 1 is read.Although only one GUID is read by this Step SA4, GUID's of all nodes arewill be read by repeating Step SA4. Thereafter, the flow advances to thenext Step SA5.

At Step SA5, it is checked whether GUID read at Step SA3 of thedominated node to be managed is equal to GUID read at Step SA4. Ifequal, the flow advances to Step SA6 indicated by a YES arrow, whereasif not, the flow skips to Step SA10 indicated by a NO arrow.

At Step SA6, a confliction adjustment process described later isexecuted. The confliction adjustment process is a process for preventinga confliction between other dominating nodes in the management of thedominated node. Then the flow advances to the next Step SA7.

At Step SA7, necessary information for managing the dominated node isread from the configuration ROM of the dominated node that the GUID isagreed with a GUID of a dominated node to be managed at Step SA5. Thenthe flow advances to the next Step SA8.

At Step SA8, in accordance with the information read at Step SA7, asoftware instance (an upper layer of the dominated node to be managed)corresponding to the dominated node is created in the upper layer of thedominating node. Thereafter, the flow advances to the next Step SA9.

Creating the software instance corresponding to the dominated node is toset the state of the dominating node so as to allow the upper node ofthe dominating node to acknowledge the command (such as an AV/C command)that the upper layer of the dominated node should originallyacknowledge. That is, after this process at Step SA8, the dominatingnode can acknowledge a command transmitted from another node to thedominated node under management of the dominating node.

At Step SA9, information of functions of the dominated node isadditionally written in the configuration-ROM of the dominating node. Itis therefore possible that another node can patent as if the dominatingnode has functions of the dominated node. Thereafter, the flow advancesto the next Step SA10.

Functions corresponding to the upper layer of a dominated node to bemanaged among the upper layers prepared in advance by the dominatingnode are written in the configuration-ROM of the dominating node, butfunctions corresponding of the upper layer of a dominated node not to bemanaged are not written in the configuration-ROM.

At Step SA10, it is checked whether GUID's of all nodes connected to theIEEE1394 bus 1 are read. If read, the flow advances to Step SA11indicated by a YES arrow, whereas if not, the flow returns to Step SA4indicated by a NO arrow to repeat the succeeding Steps.

At Step SA11, a completion notice of dominated node management settingis issued to other nodes in order to make the other nodes recognize thatthe dominated node is already managed. Thereafter, the flow advances tothe next Step SA12 whereat the dominated node management setting processis terminated.

At Step SA11, a bus reset may be issued to make other nodes connected tothe same IEEE1394 bus 1 as that of the dominating node recognize thesoftware instance created in the upper layer of the dominating node. Inthis case, the other nodes can patent as if there is a dominated node 3a with the upper layer.

Also, the dominating node can patent to have a function of the dominatednode. A command corresponding to a function of the upper layer of thedominated node to be managed is transmitted to the dominating node.

The lower layer can directly process transmissions based on isochronouscommunications so that a command is directly transmitted to a dominatednode without involving the dominating node. After the dominated nodemanagement setting process, the dominating node can process all accessesto the upper layer of a dominated node under management of thedominating node, and if necessary, can issue a predetermined transactionto a corresponding dominated node to confirm or change the operationstate of the dominated node.

When a new dominated node is connected to the bus or when the connecteddominated node is disconnected from the bus, the dominating nodeexecutes the process shown in FIG. 7 in response to the generated busreset. In this case, functions of the new dominated node are written inthe configuration-ROM of the dominating node, or functions of thedisconnected dominated node are erased from the configuration-ROM.

FIG. 8 is a flow chart making easy to understand the concept of aprocess at each node during communications illustrated in FIG. 6. It isassumed that the dominating node has already executed the dominated nodemanagement setting process shown in FIG. 7. An arrow with a broken lineshaft indicates a transmission of a packet.

Steps SB1 to SB4 are processes to be executed at a command issuing side(the general node 2 a shown in FIG. 6). At Step SB1, the command issuingside process starts and the flow advances to the next Step SB2.

At Step SB2, a command for a software instance (the upper layer B of thedominating node 4 shown in FIG. 6) corresponding to a function of thedominated node is transmitted. Thereafter, the flow advances to the nextStep SB3. The transmitted command is received by the dominating node atStep SB6 to be later described.

At Step SB3, the command issuing side receives a process result at thedominated node transmitted from the dominating node at Step SB9 to bedescribed later. Thereafter, the flow advances to Step SB4 whereat thecommand issuing side process is terminated.

Steps SB5 to SB10 are processes to be executed at the dominating node(the dominating node 4 shown in FIG. 6). At Step SB5, the dominatingnode process starts and the flow advances to the next Step SB6.

At Step SB6, the dominating node receives the command for the softwareinstance (the upper layer B of the dominating node 4 shown in FIG. 6)corresponding to the function of the dominated node and created in theupper layer of the dominating node. Thereafter, the flow advances to thenext Step SB7.

At Step SB7, a write instruction is transmitted to the function registerof the dominated node. Thereafter, the flow advances the next Step SB8.As described earlier, the dominating node stores the functions of eachdominated node managed by the dominating node in the configuration-ROM.The dominating node also stores a variety of pieces of information forcontrolling each dominated node in a working memory of the dominatingnode. This information includes information of functions of eachdominated node, an address of the function register of each dominatednode corresponding to each function, and the like. The transmitted writeinstruction is received by the dominated node at Step SB12 to bedescribed later.

At Step SB8, the dominating node receives the process result at thedominated node transmitted at Step SB14 to be described later.Thereafter, the flow advances to the next Step SB9.

At Step SB9, the process result at the dominated node received at StepSB8 is transmitted to the command issuing side. Thereafter, the flowadvances to the next Step SB10 to terminate the dominating node process.

Steps SB11 to SB15 are processes to be executed by the dominated node(the dominated node 3 a shown in FIG. 6).

At Step SB11, the dominated node process starts and the flow advances tothe next Step SB12.

At Step SB12, the dominated node receives the write instruction to thefunction register transmitted from the dominating node at Step SB7, andwrites control data in the function register. Transmission/reception ofthe write instruction and a process based on the write instruction areperformed by the transaction layer of the lower layer. Therefore, theseoperations can be performed normally by the dominated node without theupper layer. Thereafter, the flow advances to the next Step SB13.

At Step SB13, a function corresponding to the function register isexecuted. For example, predetermined values or the like are written inthe function register. Thereafter, the flow advances to the next StepSB14.

At Step SB14, the process result of the write instruction is transmittedto the dominating node. Thereafter, the flow advances to the next StepSB15 to terminate the dominated node process. FIG. 9 is a flow chartshowing a confliction adjustment process according to the embodiment ofthe present invention. The confliction adjustment process is to adjust aconfliction that can be occurred, for example when two or more than twodominating node which are on the same bus as shown in FIG. 1 (thedominating nodes 4 a and 4 b) manage one dominated node (dominated node3 a).

For example, in the case that there is the dominating node (for example,a mixer) on the bus already, other dominating node that is consisted ofa computer with a higher performance and the like is connected. Thenwhen the dominated node instead of the already existing dominating nodeis executed, the process is executed.

Also, for example, in the case that the dominating node that manages thedominated node is disconnected from the bus and that the power is turnedoff, the process is executed for managing the dominated node by otherdominating node by bus reset issued at that time.

At Step SC1, the confliction adjustment process is started and the flowadvances to the next Step SC2. At Step SC2, a storage area M1 (FIG. 2)of the dominated to be managed or to be desired is read. Then the flowadvances to the next Step SC3.

At Step SC3, it is judged whether a value of the storage area M1 that isread at Step SC2 is “0” or not. When the value of the storage area M1 is“0”, the flow advances to Step SC4 indicated by a YES arrow. When thevalue of the storage area M1 is not “0”, that is, when a GUID of otherdominating node is stored, the flow advances to Step SC5 indicated by aNO arrow.

At Step SC4, its own GUID is written in the storage area M1 of thedominated to be managed or to be desired is read. By that, starting ofmanagement of the dominated node can be informed to other dominatingnode. Then the flow advances to Step SC14.

At Step SC5, the GUID of the storage area M1 of the dominated node thatis read at Step SC2 is memorized in the register. The GUID that ismemorized in the register is used for a confirming process describedlater. Then the flow advances to the next Step SC6.

At Step SC6, the storage area M3 (FIG. 2) of the dominated to be managedor to be desired is read, and it is judged whether the value is “0” ornot. When the value of the storage area M3 is “0”, the flow advances toStep SC7 indicated by a YES arrow. When the value of the storage area M3is not “0”, that is, when the value of the storage area M3 is “1” andwhen other temporal dominating node manages temporarily, the flowadvances to Step SC15 indicated by a NO arrow. Then management of thedominated node is abandoned.

At Step SC7, it is detected whether there is a dominating node that hasa GUID stored in the storage area M1 of the dominated node on the bus ornot. When there is the dominating node on the bus, the flow advances toStep SC10 indicated by a YES arrow. When there is not, the flow advancesto Step SC8 indicated by a NO arrow.

At Step SC8, a value of the storage area M2 of the dominated node (FIG.2) is read, and it is judged whether the value is “1” or not. When thevalue of the storage area M2 is “1”, that is, when the dominated node isin a state of being possible of temporal management, the flow advancesto Step SC9 indicated by a YES arrow. When the value of the storage areaM2 is “0”, that is, when the dominated node is in a state of beingimpossible of temporal management, the flow advances to Step SC15indicated by a NO arrow. Then management of the dominated node isabandoned.

At Step SC9, the value “1” is written in the storage area M3 of thedominated node, and its own GUID is written in the storage area M4 (FIG.2). Then it is informed to other node that the temporal dominating nodemanages the dominated node at the present time. Then the flow advancesto Step SC14.

At Step SC10, permission for managing the dominated node is requested tothe dominating node that has a GUID stored in the storage area M1 of thedominated node. When there is response from the dominating node that hasa GUID stored in the storage area M1 of the dominated node, the flowadvances to the next Step SC11.

At this time, the dominating node that is requested permission ofmanagement of the dominated node responses permission (temporalpermission or complete permission) or rejection (prohibition) to thedominating node that is a requesting side. When the management of thedominated node is permitted, the dominating node requested permission ofthe management of the dominated node suspends management of thedominated node temporarily or completely.

The temporal permission is a permission that is given when restorationof a management right of the dominated node is requested by a managementright claiming process described later without completely renouncing theright of management. The complete permission is a permission that isgiven when the management of the dominated node is not executed aftergiving a complete management right to the dominating node that is arequesting side when the dominating node requested for the allowance ischanged to new one.

At Step SC11, it is judged whether the permission of the management ofthe dominated node is received from the dominating node that has a GUIDstored in the storage area M1 of the dominated node or not. When thepermission is obtained, the flow advances to Step SC12 indicated by aYES arrow. When the permission is not obtained, the flow advances toStep SC15 indicated by a NO arrow. Then management of the dominated nodeis abandoned.

At Step SC12, it is judged whether the permission of the management ofthe dominated node obtained from the dominating node that has a GUIDstored in the storage area M1 of the dominated node is temporalpermission or not. When it is temporal permission, the flow advances toStep SC9 indicated by a YES arrow. When it is not temporal permission,that is, when complete permission is obtained, the flow advances to StepSC13 indicated by a NO arrow.

At Step SC13, its own GUID is written in the storage area M1 of thedominated node, and the storage area M3 and M4 are cleared (a value “0”is written). By doing that, it is informed to be the dominating nodethat manages the dominated node thereafter to other node. Then the flowadvances to the next Step SC14.

At Step SC14, the confliction adjustment process is terminated to returnto Step SA7 as shown in FIG. 7, and the dominated node management isexecuted. At this time, the GUID of the storage area M1 of the dominatednode stored at Step SC5 may be deleted from the register.

At Step SC15, the dominated node management is abandoned, and the flowadvances to the next Step SC16. Then the confliction adjustment processis terminated to return to Step SA11 as shown in FIG. 7.

The management right claiming process is, for example, originally in thecase that the dominating node 4 a of FIG. 1 has a management right ofthe dominated node 3 a, and in the case that the management right istemporarily given to the dominating node 4 b by the above describedconfliction adjustment process or a later-described confirming process,the dominating node 4 a that has original management right requestsrestoring of management right of the dominated node 3 a.

At Step SD1, the management right claiming process is started, and theflow advances to the next Step SD2.

At Step SD2, a value of the storage area M3 of the dominated node to bedesired restoration of the management right is read, and it is judgedthat whether the value is “1” or not. When the value of the storage areaM3 is “1”, that is, when the dominated node is managed by the temporaldominating node, the flow advances to Step SD3 indicated by a YES arrow.When the value of the storage area M3 is “0”, the flow advances to StepSD9 indicated by a NO arrow.

At Step SD3, the GUID of the storage area M4 of the dominated node to bedesired restoration of the management right is read, and restoration ofmanagement right of the dominated node is requested to the temporaldominating node that has the GUID. Then the flow advances to the nextStep SD4.

At Step SD4, response from the temporal dominating node that has theGUID of the storage area M4 of the dominated node is received, and it isjudges whether the request for restoration of the management right iscomplied or not. Also, if there is no response, it is judged that thereis no dominating node 4 b on the bus. Then the process is executed asthe request of restoration is complied by compulsion. In the case thatrestoration of the management right is complied, the flow advances toStep SD6 indicated by a YES arrow. In the case that restoration of themanagement right is not complied for the reason that it takes time for adominated node management releasing process for restoring, the flowadvances to Step SD5 indicated by a NO arrow.

At Step SD5, it is judged whether the temporally dominating node havingthe GUID in the storage area M4 of the dominated node is currently thereleasing process for the management of the dominated node. When it isexecuting the process, an estimated time of ending the process or thetime period taking the process to be ended is requested to thedominating node, and the inquiry is executed again after the time or thetime period elapses. Even if the process is being executed, however,when it is obvious to take a long time for ending that process or theprocess is still being executed after the time or the time period, thisflow proceeds to Step SD10 as shown by an arrow marked “YES” totemporally terminating the management right restoration request process.When the process is not being executed or there is no responseindicating the progress

At Step SD6, a value “0” is written in the storage area M2 of thedominated node, and the dominated node is made to be into a state oftemporally unavailable for being managed. Then the flow advances to thenext Step SD6.

At Step SD8, a value “1” is written in the storage area M2 of thedominated node, and the dominated node is made to be into a state oftemporally unavailable for being managed. Then the flow advances to thenext Step SD9.

At Step SD9, the processes Step SA7 to SA9 are executed; thereafter thedominated node management is executed. Then the flow advances to thenext Step SD10 to terminate the management right claiming process.However, the processes Step SD6 and SD8 may be omitted except when thetemporal management by other node is permitted again.

FIG. 11 is a flow chart showing a confirming process to other dominatingnode in the dominating node 4 according to the embodiment of the presentinvention. This confirming process is a process for confirming whetherthe dominating node that manages the dominated node at the present time(the dominating node that the GUID is written in the storage area M1 ofthe dominated node) normally manages the dominated node on the bus ornot. Further, this process is executed by each dominated node.

By starting this confirmation process at a predetermined cycle, in thecase that the dominating node 4 b that manages the dominated node atpresent time can not execute the dominated node management for somereasons, for example, hung-up or freeze of the software, the dominatednode can be temporarily managed instead of the present dominating node 4b. Therefore, even if there is a problem in the dominating node 4 b thatmanages the dominated node at present time, a function of the dominatednode can be used by a third node included the dominating node 4 a.

At Step SE1, the confirming process is started, and the flow advances tothe next Step SE2. Further, this confirming process is, for example, aninterrupt process booted at regular intervals such as at one-secondintervals in the case that the GUID of other dominating node is storedin the register.

At Step SE2, it is judged whether there is a dominating node that hasthe GUID stored in the register at Step SC5 in FIG. 9 or not. That is,it is confirmed whether the node normally response or not. When there ison the bus, the flow advances to Step SE12 indicated by a YES arrow toterminate the confirming process.

The processes Step SE3 to SE5 are the same as the processes Step SC2 toSC4 in FIG. 9.

The process of Step SE6 is the same process as Step SC6 in FIG. 9, andthe processes of Step SE7 and SE8 are the same processes as Step SC8 andSC9 in FIG. 9.

The processes Step SE9 to SE11 are the same as the processes Step SA7 toSA9 in FIG. 7. Then the flow advances to Step SE12 to terminate theconfirming process.

Further, after Step SE11, the GUID stored in the register may bedeleted.

According to the embodiment, an IEEE1394 device serving as a dominatingnode can manage an apparatus (dominated node) complied with the IEEE1394Standard and without the upper layer

A single dominating node can manage a plurality of dominated nodes. Itis therefore easy to update the upper layer complied with the IEEE1394Standard such as a user interface, without updating each apparatusseparately and independently. Updating includes not only “updating anupper level protocol” but also “fixing bugs” and “improving theperformance”.

Since the upper layer is implemented in the dominating node, a nodewithout the upper layer can be realized while maintaining compatibilitywith the upper layer complied with the IEEE1394 Standard.

Also, an IEEE1394 device corresponding to a general node can thereforecontrol the dominated node via the dominating node.

Since the upper layer is omitted from the dominated node, hardware andsoftware resources necessary for the upper layer can be omitted, and thedominated node can be manufactured at a low cost.

Even if some or all of the functions of the upper layer of a dominatednode are suspended, the dominated node can be managed by the dominatingnode. In this case, updating the upper layer of the dominating node isequivalent to updating the upper layer of the dominated node.

Even if the upper layer is defined by new IEEE1394 Standard, thedominated node can be made complied with the new IEEE1394 Standard onlyby updating the upper layer of the dominating node.

If the dominating node is a personal computer or the like capable ofexecuting a plurality of software pieces (upper layers) for managingdominated nodes, GUID of the dominated node managed by each softwarepiece is managed and stored. In this manner, it becomes possible toavoid contention such as managing one dominated node by a plurality ofsoftware pieces.

Also, according to the embodiment of the present invention, in the casethat there is plurality of dominating nodes on the same bus, theconfliction between the dominating nodes can be prevented by inquiringwhether management is possible or not to the dominated node.

Also, in the case that the dominating node under managing is in anon-active state, or in the case that there is not on the bus, otherdominating node can temporarily manage the dominated node by inquiringto the dominated node.

Also, according to the embodiment of the present invention, since theGUID of the dominating node that manages at present time in thedominated node is recorded, the dominating node that desires thedominated node management can prevent conflictions by requesting thedominated node management to the dominating node that has the GUIDrecorded in the dominated node.

Also, according to the embodiment of the present invention, in the casethat the dominating node under managing becomes to be unable to managethe dominated node normally for some reasons, for example, the dominatednode can be managed temporarily by other dominating node by theabove-described confirming process.

Moreover, according to the embodiment of the present invention, however,only the dominating node can clear (a value “0” is written) the storagearea of the dominated node, the dominated node itself may preferablyclear the storage area. Even if the dominating node that the GUID isstored in the storage area does not connect to the same bus by keepingthe management right of the dominated node, other dominating node canobtain the management right by clearing the storage area by thedominated node itself.

The functions of the embodiment may be realized by a commerciallyavailable computer installed with a computer program and the likerealizing the embodiment functions.

In such a case, computer readable storage media such as a CD-ROM and afloppy (trade-mark) disk storing the computer program and the likerealizing the embodiment functions may be supplied to users.

If a computer is connected to a communication network such as a LAN, theInternet and telephone lines, the computer program and the like may besupplied via the communication network.

The present invention has been described in connection with thepreferred embodiments. The invention is not limited only to the aboveembodiments. It is apparent that various modifications, improvements,combinations, and the like can be made by those skilled in the art.

1. A communication apparatus constituting one node having a layeredstructure consisting of at least a first lower layer having a firstregister, a first upper layer that manages the first lower layer and asecond upper layer that manages a second lower layer of a specificdominated node connected to a network, wherein an operation of the firstlower layer is controlled by data stored in the first register, theapparatus comprising: a communication device included in the lower layerof said node that transmits/receives a signal to/from another node whichis connected to the network and generates a first instruction and asecond instruction; a first generating device included in the upperlayer that generates a first control signal in accordance with the firstinstruction received from said another node via the network; a firstwriting device that writes the first control signal to the firstregister to control the operation of the first lower layer; a managementinformation reading device that reads management informationrepresenting management status of a dominated node stored in thedominated node connected via the network; and a management informationwriting device that writes identification information of the one nodeinto a storage area of the management information in the dominated nodevia the network when the management information does not includeidentification information of other dominating node, and when theidentification information of the one node is written into the dominatednode as a part of the management information, the communicationapparatus operates as a proxy of the specific dominated node, and thecommunication apparatus further comprises: a second generating deviceincluded in the second upper layer that generates a second controlsignal for controlling the second lower layer of the specific dominatednode in accordance with the second instruction received from saidanother node via the network; and a second writing device that writesthe second control signal to a second register of the second lower layerof the specific dominated node via the network to control the operationof the second lower layer.
 2. A communication apparatus according toclaim 1, further comprising: a request receiving device that receives arequest for permission for managing the specific dominated node fromother dominating node via the network; and a responding device thatresponds to the other dominating node via the network with permission tomanage or rejection of the request in response to the received request,wherein the communication apparatus pauses the operation as a proxy ofthe specific dominated node when the responding device responds to theother dominating node with permission to manage.
 3. A communicationapparatus according to claim 2, further comprising a restorationrequesting device that requests restoration of a management right of thedominated node to the other dominating node after the responding deviceresponds to the other dominating node with permission to manage.
 4. Acommunication apparatus according to claim 2, wherein the permission tomanage is either temporal permission or complete permission.
 5. Acommunication apparatus according to claim 1, further comprising: arequesting device that requests permission to manage the dominated nodeto other dominating node when the management information includesidentification information of the other dominating node, and wherein themanagement information writing device writes the identificationinformation of the one node into the dominated node when thecommunication apparatus receives the permission from the otherdominating node.
 6. A communication apparatus according to claim 5,wherein the permission received is temporal permission and themanagement information writing device writes the identificationinformation to a storage area of the dominated node different from astorage area where the identification information of the otherdominating node is written.
 7. A communication apparatus according toclaim 6, wherein the other dominating node requests restoration ofmanagement right to the communication apparatus after the otherdominating node responses to the temporal permission.
 8. A communicationapparatus according to claim 5, wherein the permission received iscomplete permission and the management information writing deviceoverwrites the identification information to a storage area of thedominated node where the identification information of the otherdominating node has been written.
 9. A communication apparatus accordingto claim 1, further comprising: a confirming device that confirmswhether the other dominating node is managing the dominated node or notwhen the management information includes identification information ofthe other dominating node, and wherein the management informationwriting device writes the identification information of the one nodeinto the dominated node when the other dominating node is not managingthe dominated node.
 10. A communication apparatus according to claim 9,wherein the confirming device starts the confirmation at regularintervals when the management information includes identificationinformation of the other dominating node.
 11. A communication apparatusaccording to claim 9, further comprising judging device that judgeswhether temporary management of the specific dominated node is possibleor not based on the management information, and wherein the managementinformation writing device writes the identification information of theone node to a storage area of the dominated node different from astorage area where the identification information of the otherdominating node is written when the temporary management is possible anddoes not write the identification information when the temporarymanagement is not possible.
 12. A communication apparatus according toclaim 1, further comprising a storage device that stores informationabout functions of the specific dominated node when the communicationapparatus operates as a proxy of the specific dominated node.
 13. Acommunication apparatus as a dominated node connected to a network,having a layered structure consisting of at least a lower layer having aregister, wherein an operation of the lower layer is controlled by datastored in the register, the apparatus comprising: a communication deviceincluded in the lower layer of said node that transmits/receives asignal to/from other nodes connected to the network and generates aninstruction; and a storage device that stores management informationrepresenting a management status of the lower layer device, wherein themanagement information includes first data representing a dominatingnode and second data concerning to a temporary management, and when thesecond data indicates that the dominated node is not temporarily managedby other dominating node, the dominating node having an upper layeroperates as a proxy of the dominated node, namely the dominating nodegenerates the control signal in accordance with the instruction andwrites the control signal to the register via the network, and when thesecond data indicates that the dominated node is temporarily managed byother dominating node, the other dominating node having an upper layeroperates as a proxy of the dominating node instead of the dominatingnode.
 14. A communication apparatus according to claim 13, wherein thesecond data includes a flag showing whether temporary management by theother dominating node is possible or not.
 15. A communication apparatusaccording to claim 13, wherein the second data includes a flag showingwhether the dominated node is temporary managed by the other dominatingnode or not.
 16. A communication apparatus according to claim 13,wherein the second data includes identification information of the otherdominating node which operates as a proxy of the dominated node insteadof the dominating node.
 17. A communication system, comprising: adominated node connected to a network, having a layered structureconsisting of at least a lower layer having a register, wherein anoperation of the lower layer is controlled by data stored in theregister, the apparatus comprising: a communication device included inthe lower layer of said node that transmits/receives a signal to/fromother nodes connected to the network and generates an instruction; and astorage device that stores management information representing amanagement status of the lower layer device, wherein the managementinformation includes first data representing a dominating node andsecond data concerning to a temporary management, and when the seconddata indicates that the dominated node is not temporarily managed byother dominating node, a first dominating node having an upper layeroperates as a proxy of the dominated node, namely the first dominatingnode generates the control signal in accordance with the instruction andwrites the control signal to the register via the network, and when thesecond data indicates that the dominated node is temporarily managed bya second dominating node, the second dominating node having an upperlayer operates as a proxy of the dominating node instead of the firstdominating node; the first dominating node having a layered structureconsisting of at least a first lower layer having a first register, afirst upper layer that manages the first lower layer and a second upperlayer that manages a second lower layer of the dominated node connectedto the network, wherein an operation of the first lower layer iscontrolled by data stored in the first register, the apparatuscomprising: a communication device included in the lower layer of saidnode that transmits/receives a signal to/from other node connected tothe network and generates a first instruction and a second instruction;a first generating device included in the upper layer that generates afirst control signal in accordance with the first instruction receivedfrom said other node via the network; a first writing device that writesthe first control signal to the first register to control the operationof the first lower layer; a management information reading device thatreads the management information representing management status of thedominated node stored in the dominated node connected via the network;and a management information writing device that writes identificationinformation of the first dominating node into the storage area of themanagement information in the dominated node via the network when themanagement information does not include identification information ofother dominating node, and when the identification information of thefirst dominating node is written into the dominated node as a part ofthe management information, the first dominating node operates as aproxy of the dominated node, and the first dominating node furthercomprises: a second generating device included in the second upper layerthat generates a second control signal for controlling the lower layerof the dominated node in accordance with the second instruction receivedfrom said other node via the network; a second writing device thatwrites the second control signal to a second register of the secondlower layer of the specific dominated node via the network to controlthe operation of the second lower layer; a request receiving device thatreceives a request for permission for managing the dominated node from asecond dominating node via the network; and a responding device thatresponds to the second dominating node via the network with permissionto manage or rejection of the request in response to the receivedrequest, wherein the first dominating node pauses the operation as aproxy of the dominated node when the responding device responds to thesecond dominating node with permission to manage; and the seconddominating node having a layered structure consisting of at least afirst lower layer having a first register, a first upper layer thatmanages the first lower layer and a second upper layer that manages asecond lower layer of the dominated node connected to the network,wherein an operation of the first lower layer is controlled by datastored in the first register, the apparatus comprising: a communicationdevice included in the lower layer of said node that transmits/receivesa signal to/from other node connected to the network and generates afirst instruction and a second instruction; a first generating deviceincluded in the upper layer that generates a first control signal inaccordance with the first instruction received from said other node viathe network; a first writing device that writes the first control signalto the first register to control the operation of the first lower layer;a management information reading device that reads the managementinformation representing management status of the dominated node storedin the dominated node connected via the network; a requesting devicethat requests permission to manage the dominated node to the firstdominating node when the management information includes identificationinformation of the first dominating node; and a management informationwriting device that writes identification information of the seconddominating node into the storage area of the management information inthe dominated node via the network when the second dominating nodereceives the permission from the first dominating node.
 18. Acommunication method for one node having a layered structure consistingof at least a first lower layer having a first register, a first upperlayer that manages the first lower layer and a second upper layer thatmanages a second lower layer of a specific dominated node connected to anetwork, wherein an operation of the first lower layer is controlled bydata stored in the first register, the method comprising the steps of:(a) transmitting/receiving a signal to/from another node which isconnected to the network and generating a first instruction and a secondinstruction; (b) generating a first control signal in accordance withthe first instruction received from said another node via the network;(c) writing the first control signal to the first register to controlthe operation of the first lower layer; (d) reading managementinformation representing management status of a dominated node stored inthe dominated node connected via the network; and (e) writingidentification information of the one node into a storage area of themanagement information in the dominated node via the network when themanagement information does not include identification information ofother dominating node, and when the identification information of theone node is written into the dominated node as a part of the managementinformation, the one node operates as a proxy of the specific dominatednode, and the communication method further comprises the step of: (f)generating a second control signal for controlling the second lowerlayer of the specific dominated node in accordance with the secondinstruction received from said another node via the network; and (g)writing the second control signal to a second register of the secondlower layer of the specific dominated node via the network to controlthe operation of the second lower layer.
 19. A communication methodaccording to claim 18, further comprising the step of: (h) requestingpermission to manage the dominated node to other dominating node whenthe management information includes identification information of theother dominating node, and wherein the step (e) writes theidentification information of the one node into the dominated node whenthe permission from the other dominating node is received.
 20. Acommunication method for a dominated node connected to a network, havinga layered structure consisting of at least a lower layer having aregister, wherein an operation of the lower layer is controlled by datastored in the register, the method comprising the steps of: (a)transmitting/receiving a signal to/from other nodes connected to thenetwork and generating an instruction; and (b) storing managementinformation representing a management status of the lower layer device,wherein the management information includes first data representing adominating node and second data concerning to a temporary management,and when the second data indicates that the dominated node is nottemporarily managed by other dominating node, the dominating node havingan upper layer operates as a proxy of the dominated node, namely thedominating node generates the control signal in accordance with theinstruction and writes the control signal to the register via thenetwork, and when the second data indicates that the dominated node istemporarily managed by other dominating node, the other dominating nodehaving an upper layer operates as a proxy of the dominating node insteadof the dominating node.
 21. A storing medium storing a program torealize a communication process by one node having a layered structureconsisting of at least a first lower layer having a first register, afirst upper layer that manages the first lower layer and a second upperlayer that manages a second lower layer of a specific dominated nodeconnected to a network, wherein an operation of the first lower layer iscontrolled by data stored in the first register, the program comprisingthe instructions for: (a) transmitting/receiving a signal to/fromanother node which is connected to the network and generating a firstinstruction and a second instruction; (b) generating a first controlsignal in accordance with the first instruction received from saidanother node via the network; (c) writing the first control signal tothe first register to control the operation of the first lower layer;(d) reading management information representing management status of adominated node stored in the dominated node connected via the network;and (e) writing identification information of the one node into astorage area of the management information in the dominated node via thenetwork when the management information does not include identificationinformation of other dominating node, and when the identificationinformation of the one node is written into the dominated node as a partof the management information, the one node operates as a proxy of thespecific dominated node, and the communication method further comprisesthe step of: (f) generating a second control signal for controlling thesecond lower layer of the specific dominated node in accordance with thesecond instruction received from said another node via the network; and(g) writing the second control signal to a second register of the secondlower layer of the specific dominated node via the network to controlthe operation of the second lower layer.
 22. A storing medium storingthe program according to claim 21, further comprising the instructionsfor: (h) requesting permission to manage the dominated node to otherdominating node when the management information includes identificationinformation of the other dominating node, and wherein the instruction(e) writes the identification information of the one node into thedominated node when the permission from the other dominating node isreceived.
 23. A storing medium storing a program to realize acommunication process by a dominated node connected to a network, havinga layered structure consisting of at least a lower layer having aregister, wherein an operation of the lower layer is controlled by datastored in the register, the program comprising the instructions for: (a)transmitting/receiving a signal to/from other nodes connected to thenetwork and generating an instruction; and (b) storing managementinformation representing a management status of the lower layer device,wherein the management information includes first data representing adominating node and second data concerning to a temporary management,and when the second data indicates that the dominated node is nottemporarily managed by other dominating node, the dominating node havingan upper layer operates as a proxy of the dominated node, namely thedominating node generates the control signal in accordance with theinstruction and writes the control signal to the register via thenetwork, and when the second data indicates that the dominated node istemporarily managed by other dominating node, the other dominating nodehaving an upper layer operates as a proxy of the dominating node insteadof the dominating node.